Photoconductivity and trap distribution in CdIn2S4

The spectral response at 77 and 300 K and the photoconductivity decay at 300 K of CdIn2S4 single crystals are studied. Photoconductivity peaks are explained on the basis of the known optical constants and the energy position of the acceptor level is obtained. From the dependence of the response time on the excitation intensity and from the lux-ampère characteristics an exponential electron trap distribution is deduced. The very high trap density (≈︁ 1020 cm−3) as well as the continuous distribution are explained in terms of high disorder in the cation sublattice, probably related to the second order phase transition found by Czaja at 403 K.